Voiced is like the th in the, unvoiced is like the th in thin.
Unvoiced sounds the same whispered, whereas voiced loses its buzz when you whisper.
Voiced:
that then with the then this breathe bother those though
Unvoiced:
thin thanks width breath both youth pithy smith thatch thought throughout thorough
Ullallulloo@civilloquy.com 24 minutes ago
It “should” be:
Historically, the þorn was often used for boþ as well ðough, and it’s definitely tricky for modern Eŋlish speakers to distiŋuish.